Grate structure



. Zaad/Zl GRATE STRUCTURE Filed Aug. 5. 1921 D. s. VAN wAGENnN Feb. 8,1925?.

Patented F eb. 8, 1927.

noNALns. VAN'WAGENEN,orYBnooKLYN, NEW lroars, Assrenoa, 'BY Mnsnn Assis-N- MENTS, or oNnHAnr To BENJAMIN F. Watkins,l or PHrLADELrHIA, rannsrn vANjIA'.

GRATE STRUCTURE 1 Applicationmee` August 5, 1921; semi No. senesi Y- My invention relates to grate structures of the typeformingfthevsubjectof vmy copending. application, SerialNumber 447,199, iiled February 23,V 1921, the ob]ect of: the V5 present invention being to lprovide means 'whereby a superior distribution of the air through the hollow burnersis obtained, with y,

a consequent (material increase in the eili- 'ciency of the grate. l0

With this object-in view, I havel designed,

combined and arranged the several parts .hereinafter more fully disclosed and illustrated in the accompanying drawings, 1n which: 4

Figure 1, is a transverse section of the fire-box of a boiler equipped with la grate structure made in accordance with my ine vention, and y Fig. 2, is a sectional view taken on the line Qf-Q, Fig. 1, illustratingv the manner in whichthe air is introduced into the hollow grate bar sections from the expanding cham-V ber. Y Y

In its preferredv embodiment, my invention comprises a series of hollow grate bars a or burners 1 which are mounted in the fireboX of a boiler to constitute the .fuel-sup# porting bed, there beingprovided means for introducing air into the interior of the hol- 30 low grate bars, which latter are provided 1n their upper wall with suitable slots or open-- ings through .which the said draft air passes,

the air in this manner being distributed oyerv the entire area of the fuel bed. In the present instance, I have illustrated the` bars 1 Vsupported at Athe front of the boiler upon anv angle, beam 2,-'and at the rear by the bridge wall, which latter is-made hollow, the rear ends of the burners being open and being `inserted through suitable apertures 4 inthe side of the bridge' wall, whereby the Y. burners are madel to communicate with the chamber 5 'in the interiorthereof. The ex-4 tremities of the bar being fixed, it is necesf sary to provide means intermediate'the ends 55 by interposing between the vsourcean'd the bars.

blower to the chamber. to take up the expansion in the bar, and thisy bars a chamber fromffwhich the air is taken bythe. bars through uniformopenings. The

Vchamber kshouldbe of,Y such size and theadmission and exhaust openings .so disposed .that none' Yofthea-irforced into the chamber canx-passin al directcurrentto the exhaust` -V openings, and with this in view"` it is preferred to locate the exhaust openings out of theline of the current of air projected into the chamber through the admission opening. Under these circumstances it has been .found that the air instead of being driven directly into the bars or burners, which invariably results in an uneven distribution both to the individual bars and to the openings in the fuel supporting wall within the bars, expands into the bars from the chamber with a substantially even distribution7 and that furthermore the distribution within the bars totheopenings in the upper wallv is greatly improved. I have further discovered that with the above described construction, the

.draft may be controlled more satisfactorily than with other systems since the air is distributed evenly to the bars entirely regard. less of the amount of air entering the chamber or the force with which it enters.

It is preferable to placefthelsource close to the chamber and to make any duct lead'- ing from the source to the chamber increasing in cross Vsectional area toward the Lchami ber.V It is furtherdesirable toreduce the length of the .ducts between the chamber and the bars toa minimum, the ideal 4arrangement being the ent-ire eliminationl of connecting ducts by making Vthe exhaust openings of the chamber the intake openings of the l As clearly killustrated the'v drawings,

YI formthe space 5 within thebridge wall of such size as to constitute the chamber`5'the draft air being" conducted through Va duct 6 from ,a suitable source, such as a 4blower f 7, said duct Vincreasing in area` from the It will be notedthat the hollow are entirely open at one end and that'this open end'is inserted vin openings in the side of the bridge wall. There is as av result no restriction of the air inpassing into the f ice grate bars the bar from end to end with a correspond' ing even nourishment of the burning fuel over the entire bed area.

` I have further discovered that by enlarging the chamber Within the bridge Wall in a rearward direction to obtain the desired capacity and by making the top Wall over the chamber as thin as is practicable, there is obtained a very marked preheating effect on the air in the chamber, this being due to the heat conducted through the top of the bridge Wall from the' hot gases and flame Which passes over the surface.- The benefits of vpreheated air in this connection are Well understood and the arrangement provides a distinct improvement over other grate structures of this type in which the preheating effect is not obtainable.

I do not desire to restrict my invention to any particular form of hollow burner, but the burner described in my aforesaid copending application is the best form of hollow burner, since it gives a greater active grate surface, is more economical to construct and maintain, and easier to install.

I claim: n

A grate structure comprising in combination a hollou7 grate bar having openings in the upper surface thereof, an expansion chamber having unrestricted communication `with the interior of the bars, air driving mechanism, and a duct establishing c01n1nusoV nication between said chamber andv driv-v.-A

ing mechanism and increasing in cross sectional area toward the chamber.

DONALD s. lVAN WAGENEN. 

